As described in U.S. Pat. No. 4,981,225, pallet racks are commonly employed in large warehousing storage and distribution facilities, and the cells hold one or more pallets that are positioned through the use of forklifts or other similar vehicles. These vehicles load the pallet rack from its front side but frequently the design of the pallet rack and the positioning of one pallet rack relative to another is such that the operator of the forklift cannot see the back edge of a particular pallet rack cell. This, on occasion, can result in goods falling off the back side of the pallet rack including those goods on the pallet being placed on or removed from the rack, or goods on pallets already in the cell. In some instances, entire pallets can fall. Accordingly, safety guards, e.g. nets, cables, chain links, plastic webbing, tarpaulins, metal sheeting, etc., attached to the backside are desirable.
One of the earlier patents of the inventor, U.S. Pat. No. 4,981,225 which is incorporated herein by reference, describes a universal safety net system which is especially adapted for installation in connection with a wide range of pallet rack shapes, size and load requirements. The safety net system of that patent includes at least two extension assemblies for extending the effective vertical height of rear support posts of the pallet rack, each assembly including a tube and a pair of mounting plates fixed to one side of the tube. The safety net system also includes an extension boom with an extension end, the boom slidably received in the tube and longitudinally positionable at a plurality of locations. Bolts are inserted through openings in the boom and tube for fixing the length of the extension assembly, and cables are suspended between the booms.
The safety net system of U.S. Pat. No. 4,981,225 also includes offset members that can be mounted to the booms to horizontally extend the net off the back of the pallet rack. These offset members are described as square steel tubes with opposing sides having aligned equidistantly spaced perforated apertures. Welded to one end of the tube is a rectangular mounting plate, the plane of which is perpendicular to the central axis of the tube. The mounting plate has four corner openings spaced from the plate/tube intersection, and these openings are adapted to receive U-bolts by which the offset member is mounted to a support post of the pallet rack. Upon mounting, the offset member extends transversely from the pallet rack in a generally horizontal orientation.
Apertures in the steel tubes define a multiplicity of offset locations by which the safety net can be spaced from the pallet rack. Eye bolts are inserted through selective pairs of apertures such that suspension and/or support cables can be attached to the eye of the bolt and from these cables, the safety net can be attached.
While the offset members in combination with the eye bolts provide a useful system for supporting a safety net in an offset relationship from the pallet rack, this system is not without room for improvement. For example, for those offset members to which more than one net-supporting cable is attached, the use of two or more eye bolts is required. However, because each eye bolt must occupy a separate pair of aligned apertures on the square steel tube, each cable is in a different plane from the other cables. This may cause problems with the ability to maximize the tension of the net. Moreover, these eye bolts with their attendant nuts and washers can represent literally hundreds of small parts (per pallet rack) which are prone to misplacement by installers or those responsible for adjusting the net after it has been installed. Further, such installation is very labor intensive.
Another drawback to the offset member described in U.S. Pat. No. 4,981,225 is that to change the spacial distance between the safety net and the back of the pallet rack or raise or lower the top of the net on the extendable boom, requires the disengagement or loosening of the cable from the eye bolt, removal and then repositioning the eye bolt on the square steel tube, and then refastening and retightening (or retensioning) the cable to the eye bolt. Complicating this procedure even more is that often it must be preformed "in the air" (e.g. many feet above floor level) and depending upon the nature and size of the net, the net must be completely removed due to its weight (which can literally be hundreds of pounds). In those instances in which two or more nets are attached to the same offset member, changing the spacial relationship between the safety net and the pallet rack requires that this operation be repeated two or more times. In short, adjustments, like installation, to existing pallet rack guard systems can be and often are very labor intensive.